#include <iostream>
#include <fstream>

using namespace std;

int main()
{
    ifstream f ("ciur.in");
    ofstream g ("ciur.out");
    int n,i,d,s=0,ok,div;
    f>>n;
    for (i=2;i<=n;i++)
    {
        div=0;
        for (d=1;d<=n;d++)
        {
            if (i%d==0)
                div++;
        }
        if (div==2)
            s++;
    }
    g<<s;

    return 0;
}